Commercial aircraft are equipped with oxygen supply systems to be used by passengers under certain emergency conditions which have the potential of ocurring during flight. Conventionally, each seating row within the passenger compartment of an aircraft is provided with a so-called oxygen box, housing individual masks for the passengers occupying the respective seats associated with the system and a suitable supply of oxygen to those masks. The entire box is closed from the seating area by a door latched for pivotal disengagement upon actuation by a control system or a member of the flight crew; whereupon the door opens allowing the masks to drop and permitting oxygen to flow therethrough.
While the conventional oxygen supply system for commercial aircraft is a relatively straightforward assembly, many subleties attend its proper operation. For example, it is desirable to prevent passenger access to the system during normal flight conditions, yet the system must remain in a constant state of readiness should the need for its use arise. Periodic testing to insure such readiness is a mandated requirement somewhat antagonistic to the objective of individual inaccessibility. One approach to testing is simply actuation of the oxygen box array within the craft via the control system at appropriate intervals. However, the disadvantage of that type of direct approach is the collateral requirement of manually resetting each of the masks and oxygen box doors once the testing is complete. This can be both a time-consuming and tedious endeavor when one considers the numbers of oxygen box doors within even a single, large commercial aircraft, compounded by the frequency of testing and the number of aircraft involved. In an effort to obviate partially those drawbacks, several shortcuts have been adopted. For example, elastic cords or tape have been utilized to prevent complete opening of the oxygen box doors upon a test, permitting only partial opening to observe the proper actuation of the latching and release mechanisms. While this overcomes the need to reinsert masks within the oxygen box compartment itself, nonetheless the need to reset each actuator mechanism remains a significant task.
A commercial device has been introduced to improve upon the facility of testing oxygen box doors without the need to restort to elastic straps or masking tape in an effort to retard complete opening during a testing mode. That stop assembly is comprised of a reciprocable, rotatable stem having an offset test stop head at the distal end thereof. The head is usually in the form of a rectangular member mounted to the end of the stem in an offset fashion. The stem is secured by a mounting fixture within the oxygen box with the test head projecting downwardly into an aperture in the oxygen box door. The aperture is likewise generally rectangular having only a slightly oversized dimension as respects that of the test head. In normal operation, the test head resides within the aperture flush or generally flush with the face of the door to prevent passenger manipulation thereof. However, when a test of the system is required, a flat instrument may be inserted to engage a flange on the test head, draw the stem downwardly and rotate the same to present the stop member beneath the oxygen box door and, by virtue of the offset disposition of the stop head and stem, prevent the door from opening completely upon actuation of the system. The device is returned to a normal or operating configuration simply by rotating the stem and allowing the test head to retract within the aperture on the box door once the same has been reset. While a significant stride from the use of masking tape or elastic cords for this purpose, this commercial device nonetheless fails to account for the need to reset the actuating mechanism for the oxygen box door. Accordingly, the need exists for an improved test stop assembly which maintains the benefits of facilitating the testing of oxygen box doors, but one which further facilitates the ability to reset the actuating mechanisms thereof.